请教英语语言文化，关于gay

When I was young，I used to say “hey，gay！”to call my friends。But when I was older。I found it was difficult to translate it into Cinese。I think gay could be used by good friends or people who have the same background。Could you let me know what native-speakers think of this word？Is it only used by  Homosexual love？  And why I wrote it in English？Because Chin a is too  Harmony！